Antistatic photographic



A. F. SULZER.

ANTISTAUC PHOOGRAPHIC FILM.

APPLICAHUN man APR. 2s. 192|.

1 ,4: 1 8,405 Patented J une 6, 1922.

Gelatine -Jver haloid erfmld'ton lage?.

ATTORNEY possesses other useful qualities.

UNITED STATES PATENT OFFICE.

ALBERT F. sULzER, or ocHEs'rER, NEW Yom, AssrGNon 'ro EASTMAN nonni COMPANY, or ROCHESTER, NEW Yonx, A conronATxoN or NEW You ANTISTAIIC PHOTOGBAFHIC FILE.

Specication of Letters Patent.

Patented June 6, 1922.

Application tiled April 25, 1921. Serial No. 464,310.

lie it known that. l, .f'iLnnn'r F. SULZER, a citizen ol' the llnitcd States oi' America, residing` at Rochester, in the county of Monroc and State oi' New York, have invented cci-tain new and useful improvements in A\ntistatic Photographic Films, of which the following is a full clear, and exact specification.

This invention relates to anti-static photographic film. The principal object of my invention is to provide a photographic film having an inexIn-nsivc nitrocellulose base possessing the usual qualities and at the rsame time the property ot' fro-acting with the sensitized photographic layer, so as to prevent or greatly minimize static, by which is meant markings due to electrical discharges. Other objects will hereinafter ap ear.

n the handling of sensitive photographic film, particularly that of the standard type which includes a nitrocellulose support or base, characteristic lines or patches -some times appear on development, due to electrical ldischarges which are induced during such handling so as to fog the film. The preyention of this defect becomes very im portant in the motion picture field, particularly when making negative film strips.

Under certain conditions the movement of the film through the motion picture camera may cause it to be very iniuriously affected unless certain precautions are taken. While the defect appears more strongly in some types of cameras than others, and while it may to a certain extent be avoided by altentions in the camera or troublesome attachments thereto, nevertheless, it is highly desirable to 'prevent static by a proper constitution of the film itself, 'so that the latter may he employed in any commercial apparatus without precautions being necessary.

The nitrocellulose base forms a relatively inexpensive support which at the same time It is, therefore, desirable that some way be found to retain these qualities in this cheap material and at the same time prevent it from (1o-acting with the light sensitive gelatina silver lialoid layer to produce the static trouble. l have discovered that this can be accomplished by incorporating small ,a sensitive coating and a amounts of cellulose ether with the nitrocellulose.

ln the accompanying drawing, the single ligure 1s a sectional View on an exaggerated scale, o-f a film embodying my invention.

In the drawin 1 is the base or support and 2 the sensitive layer.

in carrying out one illustration of my invention I may add from 2 to 1() (preferably 5) parts of cellulose ether (say waterinsolnhle ethyl cellulose) to every 1U() parts of nitrocellulose, the union being effected by dissolving;r them in a common solvent, such, for example, as a mixture of methyl alcohol 4TH/f .cthly acetate :ZW/ and chloroform 35%. The amount of solvent that is employed relative to the wei fht of nitrocellulose and cellulose ether canv varied greatly, as will he understood by those Skilled in the art, so as to vary the rate of flow of the solutions. A useful film-forming dope may be prepared, for instance, by dissolving 100 parts of nitrocellulose and 5 parts of cellulose ether in 500 parts of the mixed volatile solvent described above.

The dope containing the nitrocellulose and ether. when thoron, hl \l mixed und filtered if desired, is flowed or deposited into thin sheets from which the volatile solvents evaporate, leaving a tough, flexible, transparent film base or support, which in all 0f its principal characteristics and in its relative cheapncss is esscntially like an ordinary nitrocellulose support. But when the usual sensitive photographic coatings are applied to such support, the latter (zo-operates with the coatings in such a way that static is prevented or very greatly minimized.

' I iaving thus described my invention, what l claim as new and desire to secure by Letters Patent is:

l. .\n anti-static photographic film having n support therefor comprising suliicientnitrmreilukise to produce, if alone, static markin in Said coutingand sufficient r-ellulose e her to prevent said static markings being prmed fn 'llid coating.

2. An anti-static photographic film com- 

